I planted 3 Arctic Frost last spring. They did well during Winter and are growing well,
Yes, but I'm in the PNW. The winters here are probably just a tiny bit milder than where you are, and we don't really have cold snaps, but the big issue is the prolonged cool to cold temperatures that last so long throughout the first part of the year. Some say it's almost like we don't have a real Spring season. The citrus did not really begin showing any signs of growth until late May to early June, with the exception of a Satsuma mandarin that was covered in plastic sheeting in a cold frame, when we had a short bout of unusually warm temperatures in April.
I'm not concerned as much about the Winter freeze as I am the constantly cold temperatures that follow for months afterwards. None of this cold is actually freezing, but it seems the citrus have difficulty dealing with it and it does cause leaf drop. I do expect, however, that once every 4 to 8 years there might be a really cold winter, but even those wouldn't be anything unusual for zone 7.
The problem isn't so much cold events, it's overall lack of warmth.